Trommel



R. D. HELLER July 13, 1937.

TROMMEL Filed Oct. 18, 1935 2 Sheets-Sheet l July 13, 1937'.

R. D. HELLER TROMMEL Filed Oct. 18, 1935 2 Sheets-Sheet 2 H) Richard D.Hellir gm A. W

Patented July 13, 1937 UNITED STATES PATENT OFFICE TROMMEL Richard D.Heller, Boise, Idaho Application October 18, 1935, Serial No. 45,554

My invention relates to trommels or screens for the purpose ofclassifying dry granular materials, as in mining operations, but itsfield of usefulness is not so limited, and it may be used wherever it isdesired to separate line material from coarser material, particularlywhere the material is formed of comparatively hard granules.

The present invention is an improvement over the invention disclosed andclaimed in my application Serial No. 727,897, filed May 28, 1934.

In the previous form of my invention, disclosed in said application,some difficulty was encountered in maintaining proper tension on thewires, all of which were originally pretensioned identically andtherefore stretched uniformly and maintained in parallelism, by reasonofbending of the cross bars to which all the wires were secured, and byreason of unequal application of tension to the wires to retension them.Accordingly one of the objects of this invention is to provide meanswhereby the wires may all be equally tensioned again to restore each oneof them individually and in relation to the others to the pretensionedrelationship or condition, and to provide means such as these which arecapable of accomplishing an even, yielding tension on all the wires.

A further object is to simplify the method of replacing worn screens.

One of the difiiculties in all parallel wire screens lies in providing aconstruction which will permit them to vibrate freely, throughout thelength which is exposed to contact with the material, so that they willclwn themselves, and 'yet to prevent passage of small bits of materialbetween the wires and the framework, 'or at the iunction of the wireswith the framework, thus to dampen vibration,--to clog or spread thewires, or otherwise to interfere with the proper functioning of themachine. Accordingly it is a further object of my invention to devisemeans cooperating between the frame and the wires mounted thereon, whichwill not damp vibration of the wires throughout their entire exposedlength, and which will prevent entrance of materials between the wiresand the frame.

More specifically it is an object to provide a resilient member,engaging the wires inwardly of their anchorage to the cross bars, whichwill prevent passage-of material between this resilient member and thewires, which will not impede vibration of the wires substantially fromone point of anchorage to the one at the opposite end, and

10 Claims. (01. 209-400) which will maintain proper spacing of the wiresat all times. I

It is a further object to reinforce the wires and furtherto impedemovement of bits of material between the wires running parallel to andadjacent to the edge of the openingthrough which the materials pass, thescreen.

These and other objects will appear as this specification progresses.

My invention comprises the novel trommel and the novel parts thereof,alone and in combination, as shown in the accompanying drawings,described in this specification, and as will be more particularlypointed out by the claims which terminate the same.

In the accompanying drawings 1. have shown my invention embodied inillustrative forms as now'preferred by me.

Figure 1 is a side elevation of a three-section trommel, with partsbroken away.

Figure 2 is an end view of such a trommel.

Figure 3 is an enlarged section on the line 3-3 of Figure 1, and Figure4 is a similar view showing a modified arrangement.

Figure 5 is a side elevation of a two-section trommel of somewhatmodified form from that shown in Figure 1.

Figure 6 is a side elevation of one of the anchorages for the wires, andFigure 7 is an elevation looking down on the same, showing exaggeratedlythe manner in which vibration is permitted in the wires. 9

In general the trommel consists of a polyhedral cylinder, set preferablyat an incline, and rotatable, whereby materials entering at one end willbe lifted and dropped repeatedly, and will slide over each screen as thetrommel rotates, and will be worked down toward the lower end, thescreens being formed of parallel tensioned wires set in general parallelto the axis of rotation, so that as the trommel rotates, the finematerial. of a size to pass between the wires, will pass between them,and larger material will remain inside the trommel, being discharged atthe lower end.

Thus in Figures 1 and 5 the rotative frame is made up of corner bars lljoined by end'bars II and at intervals by cross plates i2, ll, it and I!to leave rectangular openings II, II and it, through which the screenedmaterial passes. The whole frame is supported by spiders is upon arotative shaft l. The means for mounting and supporting the trommel, andthe classifying bins into which the screened material drops. are notwhich opening is closed by illustrated, but by way of example referencemay be made to the structure shown in my previous application, referredto above.

The wires, generally designated by the numeral 2, are permanentlysecured, as by welding or soldering, to end bars 20, about which theyare wrapped, as may be seen in the large scale view,

Figure 6. Unless, of considerable strength, these end bars will bendwhen the wire is retensioned, but by engaging the inner edge of each endbar 20 with an upstanding transverse shoulder 30, which is carried bythe rotative frame,the end bar is supported throughout its entirelength, and thus cannot bend, and therefore holds the wires in the samerelationship that they were when first secured to the end bars. Thewires may be of a length to extend across only one opening, as shown inFigure 1, or of a length to extend from end to end of the frame, acrosstwo or more openings, as shown in Figure 5. In the form shown in Figurel the shoulder 30 upon the plate ii is fixed to the latter, as by bolts3|, but the shoulders 30a; and 30b are part of a plate 32 which isslidable lengthwise of the frame, being guided on bolts 3m, and likewiseshoulders 30c and 30d are siidabiy mounted upon a plate 32, and theshoulder 304: forms part of a plate 33 which rests upon the plate l2.and which has secured toit bolts 34. Springs 35, between nuts 36 on thebolts 34 and the shoulder plate Ii, serve to draw all the wires tight,and to maintain them tensioned as they were in their originalpretensioned condition. In order to hold the several end bars 20 againsttheir respective shoulders 30, 30a, 301), etc., clamping or hold-downplates 31, 31m, 311; and 310 may be provided, these being held down bythe bolts 3|, Ila, etc. The clamping plate 310 is held down by bolts Hereceived in an overhanging flange of plate 33,

so that the latter is not guided from the frame except by the bolts 34.

Preferably the wires 2 do not lie close to the plane defined by thecorner angles 10; that is to say, there is no attempt made to keep thewires in the plane of each opening. Instead I have found it preferableto outline each opening with upstanding bars 40 which are of a height tolie just below the normal plane of the wires when stretched, and thisspace and a little more is occupied by a resilient strip of rubber orthe like,

indicated at 4. The frame thus built up lies inwardly of the points ofanchorage of the several wires, and also along each side of the opening,the wires at the sides of the opening lying.

in contact with the rubber strips 4 throughout their length, as seen inFigures 1 and 5. The rubber strips 4 serve in a sense as bridge members,the wires being slightly deflected by them to an extent sufficient topress the wires into the rubber, as may be seen in Figure 6. Inconsequence no material can pass between these wires and the rubberstrips 4. By using, live resilient rubber the tendency of the wires tovibrate from their points of anchorage, as is illustrated in Figure '7,is but little, if any, dampened by the rubber strips 4, with the resultthat the wires vibrate freely, orsubstantially so, at the point wherethey emerge into the space defining any given opening, whereas if thewires were anchored or dampened at this edge there would importance toinsure that the wires be so mounted as to vibrate freely at all pointswhere they may come in contact with the materials. and that a zone ofreduced or minimum vibration, if there be any, be outside of thescreening opening.

Various means may be employed to vibrate the wires, or to insure theirvibration. Reliancemay be placed wholly upon the action of the materialssweeping and sliding down over the wires.

or resiliently mounted picks 5 may be employed, as in my former.application, the points of these piclm engaging each individual wire inturn as the trommel rotates, and serving to set itinto vibration.

As may be seen in Figure 5, the wires may be of a length to extend fromend to end of the rotative frame, but in such cases it is preferable tohold the wires down to the frame at intermediate points, and to this endI may provide the clampingplates '8 and 60 engaging each'set of wires atan intermediate point, to prevent of which are equally tensioned, cannot bite into the longitudinally extending rubber strip 4 to quite thesame extent that they do passing over the'narrow width thereof at eachend of the screening opening; hence in order toprevent passage of largematerial or its lodgment between the wires, thus to clog the screen, Imay increase the number of wires at the sides of eachscreen. Thus, forexample, as may be seen in Figure 3, the wires may be laid in severallayers at the side edge, creating a zone close to the edge which is yetof wire and vibratory, but more dimcult for materialsv to enter or passthrough. As seen'in Figure 4, a similar result may be accomplished bydoubling the number of wires in a given transverse space.

The manner of using the screen will be evident,

and its advantages have been pointed out'hereof, whereon the wires restand into which the wires are pressed to prevent escape of materialsbetween the wires and the frame.

2. In a screen for a trommel, a frame defining an opening, a pluralityof parallel tensioned wires extending across said opening, meansdisposed on said frame outwardly of the opening to anchor the ends ofthe wires and to maintain them under tension, to vibrate, and strips oflive rubber extending transversely of I the wires, upstanding from theframe to above the level of the wires, inwardly of the anchoring means,and into which the wires are pressed, but yieldable to such vibration,yet preventing escape of materials between the wires and the frame.

3. In a screen for a trommel, a frame defining an opening, a pluralityof parallel tensioned wires extending across said opening, meansdisposed on said frame outwardly of the opening to anchor the ends ofthe wires and to maintain them under tension, to vibrate, strips of liverubber disposed inwardly of the anchoring means and extending 1transversely of the wires, and extending upwardly from the frame to alevel above that of the wires, and into which the wires are pressed, butsaid strips being yieldable to such vibration, yet preventing escape ofmaterials between the wires and the frame, and other strips of liverubber extending parallel to the wires, and similarly disposed betweenthe frame and the wires, to be pressed by the wires, and with the firstmentioned strips defining the edges of the opening and closing the spacebetween the wires and the frame, without unduly damping vibration of thewires.

4. In a screen for a trommel, a frame defining an opening, live rubberstrips upstanding from the frame entirely about the edge of saidopening, a plurality of parallel tensioned wires extending across saidopening and pressing into said rubber strips, means to anchor the endsof the wires disposed on the frame outwardly of the rubber strips, tomaintain the wires tensioned so that they will vibrate, the wiresbetween the side edges of the opening being equally spaced, and thewires along each side edge being more closely spaced.

5. A trommel comprising a rotative polyhedral frame, each side of whichhas an opening, a plurality of parallel equally tensioned wiresextending lengthwise of each side, across the opening therein, means toanchor the ends of the wires upon the frame, to maintain them tensioned,to vibrate, and a live rubber strip upstanding from 1 the frame aroundeach opening, into which the wires press at every edge of the opening.

6. In a screen for a trommel, a frame defining an opening, live rubberstrips upstanding from the edges of the opening, a plurality ofparallel, equally pretensioned wires of a length to extend across saidopening and over said strips, a cross bar at each end of the wires, towhich all the wires are permanently secured, while pretensioned, toretain them in such relationship, and

spring means urging said cross bars apart, to tension said wires equallyand to restore such wires to their pretensioned relationship, and topress them into said rubber strips.

7. In a screen for a trommel, a frame defining an opening, a pluralityof parallel, equally pretensioned wires of a length to extend acrosssaid opening, a cross bar at each end of the wires, to which all thewires are permanently secured, while pretensioned, to retain them insuch'relationship,

'an opening,

a shoulder at each end of said frame opening, whereon the correspondingcross bar bears, spaced members extending transversely of the frame andengaging the wires, intermediate their ends, a transversely extendingplate engaging the opposite sides of the wires, intermediate the spacedmembers, and means to draw said plate downward into the space betweensaid members, to tension said wires equally while the cross bars arethus engaged with said shoulders, to restore such wires to theirpretensioned relationship.

8. In a screen for a trommel, a frame defining a plurality of parallel,equally pretensioned wires of a length to span said opening, a cross barat each end of the wires, to which all the wires are permanentlysecured, while pretensioned, to retain them in such relationship, anupstanding shoulder at each end of said frame opening, whereon thecorresponding cross bar bears, a clamping plate engaging the cross, barand the wires secured thereto from above and clamping them down upon theframe, and spring means urging the shoulders and associated clampingplates apart, to tension said wires equally, and to restore the wires totheir pretensioned relationship.

9. In a screen for a trommel, a frame defining an opening, a pluralityof parallel, equally pretensioned wires of a length to extend acrosssaid opening, a cross bar at each end of the wires, to which all thewires are permanently secured, while pretensioned, to retain them insuch relationship, a shoulder at each end of said frame opening, whereonthe corresponding cross bar bears, means urging said shoulders apart, totension said wires equally while the cross bars are thus engaged withsaid shoulders, to restore such wires to their pretensionedrelationship, and a live rubber strip upstanding from the frame, insidesaid shoulders, and into which the wires are pressed, to prevent passageof material outwardly of said strips, without detracting appreciablyfrom the vibration of said wires immediately at each side of and throughsaid strip.

10. In a screen for a trommel, a frame defining an opening, a pluralityof parallel wires extending across said opening, anchored at each endthereof and tensioned, whereby they tend to define a given plane, and atransverse strip of resilient material upstanding from the frame, inwardof each end of the wires, of a height, when unrestrained, to extendabove the level of such plane, whereby the wires are pressed into suchstrip,

RICHARD D. HELLER.

